Quick battery disconnect system for high current circuits

ABSTRACT

A circuit protection system is provided herein that minimizes the disconnection time of a circuit while protecting other electrical components. Some configurations comprise a set of parallel circuit interruption devices, each connected in series with respective fuses. A control device sets a state of the circuit interruption device based on a current of the circuit. Under certain current loads, the circuit is interrupted without causing a fuse to blow. Under other current loads, the circuit is interrupted by having one or more fuses blow.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. patent application Ser. No. 16/680,790,filed Nov. 12, 2019, which claims the benefit of U.S. ProvisionalApplication No. 62/760,858, filed Nov. 13, 2018, each of which is herebyincorporated by reference herein in their entireties.

INTRODUCTION

Electric vehicles typically include a high power battery connected to aload, such as an electric drive unit. The voltage across the terminalsof such batteries can exceed 300V with an operating current exceeding500 A. Because a short circuit across the terminals can result in dangerto the occupants of the electric vehicle and/or damage to the vehicle'scomponents, conventional electric vehicles include a fuse in series withthe battery and the load to interrupt the short circuit. Typically, arated current capacity of the fuse is selected based on a maximumexpected operating current of the electric vehicle. Due to the thermal,non-linear nature of conventional fuses, as the rated current capacityof a fuse increases, so does an amount of time required to cause thefuse to interrupt the circuit. Consequently, a conventional fuse may notinterrupt a circuit quickly enough to prevent damage to the circuit.

SUMMARY

In some embodiments, a battery system is provided. The battery systemcomprises two fuses, two contactors, and one or more battery cells. Thetwo fuses, the two contactors, and the one or more battery cells eachcomprise two terminals. A first terminal of the one or more batterycells is electrically coupled in parallel to a first electrical terminalof the first fuse and of the second fuse. A second terminal of the firstfuse is electrically coupled to a first terminal of a first contactorand a second terminal of the second fuse is electrically coupled to afirst terminal of the second contactor. A second terminal of the firstcontactor and a second terminal of the second contactor are electricallycoupled in parallel (e.g., via a busbar). The first fuse and the secondfuse each comprise a locally minimum cross-sectional area configured tomelt at a predetermined current, thereby interrupting a circuit when thecurrent is surpassed.

In some embodiments, the battery system further comprises a contactorcontrol module configured to set at least one of an open state and aclosed state of the first contactor and the second contactor. In suchembodiments, the contactor control module may control the state of thefirst contactor and the second contactor via control terminals of therespective contactors. In some embodiments, the contactor control moduleis configured to set one of the first contactor and the second contactorto the open state based on detecting a current within a predeterminedamperage range. In such embodiments, the predetermined amperage rangemay be within 2,400 to 5,000 amps. In some embodiments, the contactorcontrol module is configured to maintain both of the first contactor andthe second contactor in the closed state based on detecting a currentgreater than a predetermined amperage. For example, in such embodimentsthe predetermined amperage range may be at least 5,000 amps.

In some embodiments, the battery system is located in an electricvehicle. In such embodiments, the contactor control module is furtherconfigured to detect a vehicle fault condition. In response to detectingthe vehicle fault condition, the contactor control module sets the firstcontactor to the open state and sets the second contactor to the closedstate. While the vehicle fault condition exists, the electric vehiclemay be operated in a reduced performance mode.

In some embodiments, a busbar electrically coupling the second terminalsof the first and second contactors provides switched power to theelectric vehicle. In some embodiments, a third contactor is electricallycoupled to the busbar via a first contactor terminal. The secondcontactor terminal is electrically coupled to a charging port.

In some embodiments, each of a first contactor terminal of a fourth anda fifth contactor is electrically coupled in parallel (e.g., via abusbar) to a second battery module terminal (e.g., a negatively chargedterminal). A busbar may electrically couple the second contactorterminals of the fourth and fifth contactors in parallel and may provideswitched power to the electric vehicle.

In some embodiments, a first battery module terminal is electricallycoupled to a positive terminal of the one or more battery cells, and asecond battery module terminal is electrically coupled to a negativeterminal of the one or more battery cells. The first battery moduleterminal and the second battery module terminal may be unswitchedterminals. In some embodiments, the voltage across the first batterymodule terminal and the second battery module terminal is greater than300 volts. The battery system may have a maximum operational currentthat is within 1,000 amps and 2,500 amps.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure, in accordance with one or more variousembodiments, is described in detail with reference to the followingfigures. The drawings are provided for purposes of illustration only andmerely depict typical or example embodiments. These drawings areprovided to facilitate an understanding of the concepts disclosed hereinand shall not be considered limiting of the breadth, scope, orapplicability of these concepts. It should be noted that for clarity andease of illustration these drawings are not necessarily made to scale.

FIG. 1 shows an exemplary configuration of contactors, fuses, andbattery cells, in accordance with some embodiments of the presentdisclosure;

FIG. 2 shows an additional exemplary configuration of contactors, fuses,and battery cells, in accordance with some embodiments of the presentdisclosure;

FIG. 3 shows illustrative contactors and fuses arranged in accordancewith some embodiments of the present disclosure; and

FIG. 4 shows an exemplary contactor control configuration, in accordancewith some embodiments of the present disclosure.

DETAILED DESCRIPTION

As battery technology has advanced, the voltage and operating current ofelectric vehicle battery modules has increased. A short circuit acrossthe terminals of an electric vehicle's high power battery module canresult in danger to the occupants of the vehicle and/or damage to thevehicle's components. To protect the occupants and the electricalcomponents, electric vehicles include a battery disconnection component,oftentimes a fuse, configured to disconnect power from the batteryduring an overcurrent event. Typically, a rated current capacity of thefuse is selected based on a maximum expected operating current of theelectric vehicle. Due to the thermal, non-linear nature of conventionalfuses, as the rated current capacity of a fuse increases, so does anamount of time required to cause the fuse to interrupt the circuit.Because damage caused by a short circuit event can be proportional tothe duration of the event, the increased interruption time can result indamage to the electric vehicle that could have otherwise been preventedwith quicker disconnection.

The present disclosure is directed to a system for quickly disconnectinga battery pack from a circuit in the event that the circuit isexperiencing an overcurrent event. For example, an electric circuit,such as an electric circuit in an electric vehicle, may comprise a highpower battery pack connected to a plurality of electronics, such as oneor more motors, controllers, air conditioning systems, lightingcircuitry, infotainment systems, etc., with a wiring harnesselectrically coupling the various electronics to the battery. If one ormore of the components in the circuit experiences an electrical fault(e.g., a short circuit in the harness caused by a vehicle crash or amalfunction of one of the electronics), the battery disconnect systemdescribed herein can quickly disconnect the battery from the circuit toprevent or reduce the amount of damage to the circuit components due tothe electrical fault.

FIG. 1 depicts an exemplary configuration of contactors, fuses, andbattery cells, in accordance with some embodiments of the presentdisclosure. Configuration 100 depicts contactors 104A, 104B, and 110,contactor control module 102, fuses 106A and 106B, and battery module108 arranged to reduce the amount of time required to disconnect abattery from a load under various circuit currents. The exemplary systemdepicted in configuration 100 comprises at least two parallel fusedpaths (e.g., a first path formed by contactor 104A and fuse 106A and asecond path formed by contactor 104B and fuse 106B) connected to abattery terminal (e.g., a battery terminal of battery module 108). Theparallel path is formed by electrically coupling (e.g., via a busbar) afirst fuse terminal of fuse 106A and a first fuse terminal of fuse 106Bto a first battery terminal of battery module 108 (e.g., a positivelycharged terminal).

In some embodiments, battery module 108 comprises a plurality of batterycells connected in series and parallel connections having a totalpotential exceeding 300 volts. In some embodiments, a total circuitcurrent, supplied by battery module 108, can vary between 600 amps to1,000 amps. Because the current is roughly split equally across theparallel fused paths (e.g., the first path formed by contactor 104A andfuse 106A and the second path formed by contactor 104 B and fuse 106B),the rated current of each fuse is selected such that the rated currentis less than a desired maximum operational circuit current (e.g.,600-1,000 amps). For example, in a dual fuse configuration depicted inFIG. 1 , each of fuses 106A and 106B may be selected to have a ratedcurrent of approximately one half (e.g., 300-500 amps) the desiredmaximum operational circuit current (e.g., 600-1,000 amps). Due to thethermal properties of conventional fuses, each of fuses 106A and 106B inthe dual fuse configuration (e.g., fuses with a rated current ofapproximately 300-500 amps) has a significantly lower interruption timethan would a conventional fuse having double the rated current (e.g., afuse with a rated current between 600-1,000 amps). Therefore, in anovercurrent event exceeding 1,000 amps, dual 500 amp fuses wouldinterrupt a circuit more quickly than a single fuse of 1,000 amps.

Each of the fused parallel paths comprises a respective contactorconnected in series to the fuse. For example, a first contactor terminalof contactor 104A is electrically coupled in series to a second fuseterminal of fuse 106A, and a first contactor terminal of contactor 104Bis electrically coupled to a second fuse terminal of fuse 106B. Arespective second contactor terminal of contactor 104A and contactor104B may be electrically coupled in parallel (e.g., via a busbar) to aload (e.g., a positive terminal of the load).

In some embodiments, a second set of contactors is electrically coupledto the load and the battery module. For example, a first contactorterminal of each of contactors 110 may be electrically coupled (e.g.,via a busbar) to a second terminal of battery module 108 (e.g., anegatively charged terminal). A second contactor terminal of each ofcontactors 110 may be electrically coupled in parallel to the load(e.g., a negative terminal of the load).

In some embodiments, each of contactors 104A, 104B, and 110 isconfigurable to electrically couple or decouple the circuit from thebattery terminal (e.g., based on a signal received from contactorcontrol module 102). Each of the contactors (e.g., contactors 104A,104B, and 110) have a respective maximum disconnect current and maysafely couple and decouple an electrical circuit while under a load thatis less than the maximum disconnect current. If the load exceeds themaximum disconnect current, a contactor may be damaged if decouplingoccurs. In some embodiments, each contactor (e.g., contactors 104A,104B, and 110) comprises a contactor control terminal electricallycoupled to contactor control module 102. In such embodiments, contactorcontrol module 102 controls an open state and a closed of the contactor.

In some embodiments, if the battery system detects an overcurrent eventof the circuit that is less than the maximum disconnect current of eachcontactor, contactor control module 102 may cause contactors 104A, 104Band 110 to open, thereby quickly decoupling the circuit from the batterywithout blowing the fuses. In some embodiments, in response to detectingthe overcurrent event below the maximum disconnect current of eachcontactor, the contactor control module may instruct one of contactors110 or contactors 104A and 104B to open, thereby decoupling either thefirst battery terminal or the second battery terminal of battery module108 from the circuit.

In some embodiments, if the battery system detects an overcurrent eventof the circuit that is greater than the maximum disconnect current ofeach contactor, but less than double the maximum disconnect current, thesystem may decouple one parallel path from the battery terminal (e.g.,the parallel path formed by contactor 104A and 106A), resulting in thefuse in the second parallel path (e.g., fuse 106B) to exceed the ratedcurrent and blow the fuse, thereby disconnecting the circuit. In someembodiments, the rated current of the fuses may be selected to besimilar to the maximum disconnect current of contactors. Because of thesmaller rated current of the fuse (relative to a fuse that requiresdouble the rated current), the system is able to blow one of theparallel fuses more quickly than would be necessary for a single fuserequiring double the interruption current. Because damage caused by ashort circuit event may be proportional to the duration of the event,the reduction in interruption time may result in reduced damage to thecircuit. However, because the overcurrent event of the circuit exceedsthe maximum disconnect current for the contactor (e.g., contactor 104A),the contactor will be damaged during the decoupling. In someembodiments, when the battery system is located in an electric vehicle,the battery system will maintain a record indicating that one of thecontactors is damaged and will notify an operator of the electricvehicle. In some embodiments, the electric vehicle will operate in areduced power mode (e.g., half of a current for normal operation). Uponreplacement of the damaged components the system will resume normaloperation.

In some embodiments, if the battery system detects an overcurrent eventthat is greater than double the maximum disconnect current, the batterysystem, via contactor control module 102, will maintain contactors 104A,104B, and 110 in a closed state, thereby causing fuses 106A and 106B inthe parallel paths to blow (e.g., because the current rating for thefuse is chosen to be less than or equal to the maximum disconnectcurrent of the contactor).

Although the fused parallel paths are discussed with respect to aconnection to a positive terminal of the battery, the fused parallelpaths may instead be connected to a negative terminal of the battery. Insome embodiments, a first set of parallel paths may be connected to thepositive terminal of the battery and a second parallel path may beconnected to a negative terminal of the battery.

FIG. 2 depicts an additional exemplary configuration of contactors,fuses, and battery cells, in accordance with some embodiments of thepresent disclosure. In some embodiments, the contactors (e.g.,contactors 104A, 104B, and 110), fuses (e.g., fuses 106A and 106B),contactor control module (e.g., contactor control module 102), andbattery module (e.g., battery module 108) described with respect to FIG.1 are electrically equivalent to the corresponding components depictedin FIG. 2 . In configuration 200, a fused parallel path is connected toa negative terminal of the battery module, instead of the positiveterminal of the battery module as in configuration 100. A first terminalof a first fuse (e.g., fuse 206A) and a second fuse (e.g., fuse 206B)are electrically coupled in parallel to a negative terminal of thebattery (e.g., battery module 208).

Battery module 208 may comprise a plurality of battery cells connectedin parallel and series connections having a total electrical potentialexceeding 300 volts across a most positively charged terminal of thebattery module and a most negatively charged terminal of the batterymodule. A second terminal of the first fuse (e.g., fuse 206A) iselectrically coupled to a first terminal of a first contactor (e.g.,contactor 210A). A second terminal of the second fuse (e.g., fuse 206B)is electrically coupled to a first terminal of a second contactor (e.g.,contactor 210B). The second terminals of the first and second contactorsare electrically coupled in parallel. In some embodiments, the secondterminals of the first and second contactors are electrically coupled inparallel to a busbar that provides switched power to an electricvehicle. In some embodiments, the busbar is electrically coupled to athird contactor configured to control a charging circuit of the battery(discussed further below with respect to FIG. 3 ).

A second, non-fused, parallel path is connected to a positive terminalof battery module 208. A respective first contactor terminal ofcontactors 204 is electrically coupled in parallel (e.g., via a busbar)to a positively charged terminal of battery 208. Although configuration200 depicts two contactors in the second parallel path (e.g., contactors204) one or more contactors may be used without departing from the scopeof the present disclosure. A respective second contactor terminal ofeach contactor may be electrically coupled in parallel (e.g., via abusbar). In some embodiments, the second contactor terminals areelectrically coupled to a load and/or a third contactor configured tocontrol a charging circuit of the battery.

Although configurations 100 and 200 depict the fused parallel pathshaving a terminal of the fuse electrically coupled to a battery inseries with a contactor, the order of the fuse and the contactor inseries can change without departing from the scope of the presentdisclosure. For example, a first contactor terminal of a first contactor(e.g., contactor 104A or contactor 210A) may be electrically coupled toa positive terminal of a battery module (e.g., battery module 108 or208). A second contactor terminal of the first contactor (e.g.,contactor 104A or contactor 210A) may be electrically coupled to a firstfuse terminal of a first fuse (e.g., fuse 106A or 206A). A second fuseterminal of the first fuse (e.g., fuse 106A or 206A) may be electricallycoupled to a load and the second parallel path (e.g., the seriesconnection between fuse 106B and contactor 104B or the series connectionbetween fuse 206B and 210B).

In some embodiments, when contactor control module 102 or 202 detects afault event (e.g., a vehicle crash or a short circuit), the contactorcontrol module may set the state of the first contactor (e.g., contactor104A or 210A) and/or the second contactor (e.g., contactor 104B or 210B)based on a measured current value to optimally minimize thedisconnection time (discussed further in relation to FIG. 4 ). When thecontactor control module detects a fault event and the circuit currentis below the maximum contactor disconnect current (e.g., due to acrash), the contactor control module may open both contactors (e.g.,contactors 104A and 104B or contactors 210A and 210B). When thecontactor control module detects a current overload less than twice themaximum contactor disconnect current but greater than the maximumcontactor disconnect current, the contactor control module may open acontactor on a first parallel path to increase the current on and thusoverload the fuse on the second parallel path (e.g., contactor controlmodule 202 may open contactor 210A and leave contactor 210B closed,thereby causing fuse 206B to blow and interrupt the circuit). When thecontactor control module detects a current overload that exceeds twicethe maximum contactor disconnect current, the contactor control modulemay keep both contactors closed (e.g., both of contactors 104A and 104Bor contactors 210A and 210B), causing the fuses (e.g., both of fuses106A and 106B or fuses 206A and 206B) to overload on both parallelpaths. By setting or maintaining an open or closed state for each of thecontactors under the various current conditions, the system is able tooptimally minimize disconnect time.

FIG. 3 shows illustrative contactors and fuses arranged in accordancewith some embodiments of the present disclosure. Arrangement 300 depictsan exemplary fused parallel path (e.g., one of the parallel pathsdepicted in FIGS. 1 and 2 ) coupled with a charging circuit. Inarrangement 300, busbar 306 electrically couples a respective firstcontactor terminal of first contactor 302 and second contactor 304 inparallel to a battery module terminal (e.g., a positive or negativeterminal of battery module 108 and 208). In some embodiments, contactors302 and 304 may operate in the manner described above regardingcontactors 104A and 104B in FIG. 1 and contactors 210A and 210B in FIG.2 , to reduce a disconnection time of the circuit during an overcurrentevent. In some embodiments, contactors 302 and 304 each comprise arespective contactor control terminal (e.g., contactor control terminal322 and contactor control terminal 324), which is electrically coupledto a contactor control module (e.g., contactor control module 102depicted in FIG. 1 or contactor control module 202 depicted in FIG. 2 ).The contactor control module may set a state of the contactors bysending a signal to open or close the contactors via contactor controlterminals 322 and 324.

In some embodiments, the contactor control module is configured to setthe contactor to the open state (e.g., electrically decoupling aninternal connection between the first terminal of the contactor and thesecond terminal of the contactor) or closed state (e.g., electricallycoupling an internal connection between the first terminal of thecontactor and the second terminal of the contactor), based on a circuitcurrent and/or an operating state of the vehicle. For example, when auser turns on the electric vehicle, the contactor control module may setcontactor 302 and contactor 304 to a closed state, from an open state.In another example, the contactor control module may set one or more ofcontactors 302 and 304 to an open state, from a closed state, based ondetecting an overcurrent event. In some embodiments, the contactorcontrol module selects the number of contactors to an open state duringan overcurrent event based on a detected circuit current (discussedfurther below with respect to FIG. 4 ).

A second contactor terminal of first contactor 302 is electricallycoupled to a first fuse terminal of first fuse 312 via busbar 308. Asecond contactor terminal of second contactor 304 is electricallycoupled to a first fuse terminal of second fuse 314 via busbar 310. Therespective second fuse terminals of first fuse 312 and second fuse 314may be electrically coupled in parallel via busbar 316. In someembodiments, busbar 316 is electrically coupled to a load, such as anelectric motor. A current rating of fuses 312 and 314 may be selected asdescribed above regarding fuses 106A and 106B in FIG. 1 , and fuses 206Aand 206B in FIG. 2 . For example, if an expected maximum circuit currentof the electric vehicle is 1,000 amps, the current rating for each offuses 312 and 314 may be 500 amps, half of the maximum circuit current.

In some embodiments, busbar 316 is additionally coupled to a chargingcontactor, such as contactor 318, via a first contactor terminal.Charging contactor 318 may control an inflow of current to charge abattery module (e.g., battery module 108 or 208). The contactor controlmodule (e.g., contactor control module 102 or 202) may control an openor a closed state of contactor 318 based on a charging state of thebattery. For example, the battery control module (e.g., via contactorcontrol module 108 or 208) may set contactor 318 to an open state (e.g.,via contactor control terminal 326) when the battery is not charging andto a closed state when the battery is charging.

Although FIG. 3 is depicted having parallel paths (e.g., the first pathcomprising contactor 302 and fuse 312, and the second path comprisingcontactor 304 and fuse 314, one or more paths may exist between thebattery module and the load without departing from the scope of thepresent disclosure. In some embodiments, a fuse is not placed in serieswith the contactors (e.g., depicted as contactors 110 in FIG. 1 and ascontactors 204 in FIG. 2 ). In such embodiments, the second contactorterminals of contactors 302 and 304 may be electrically coupled to thecharging contactor (e.g., contactor 318) via busbar 316, without havinga connection to busbars 308 and 310, or fuses 312 and 314.

FIG. 4 depicts an exemplary contactor control diagram, in accordancewith some embodiments of the present disclosure. Diagram 400 visuallydepicts how the contactor control module may determine whether or not toopen one or more contactors during an overcurrent event, based on thecircuit current. In diagram 400, the contactor control module sets thecontactors (e.g., contactors 302 and 304) to first state 402 when thecircuit current is below first threshold 408; sets the contactors tosecond state 404 when the circuit current is within first threshold 408and second threshold 410; and sets the contactors to third state 406when the circuit current is above second threshold 410. The variousstates and thresholds depicted in diagram 400 may be selected based onthe electrical parameters of components in the electric vehicle (e.g.,current ratings of the fuses and contactors, a maximum circuit current,disconnect times, etc.) and are optimized to reduce the disconnect timeduring an overcurrent event and protect the electric vehicle'scomponents. For example, contactors may be able to interrupt a circuitmore quickly than a fuse under a same circuit current. However, acontactor may only interrupt a circuit without causing damage to thecontactor when the circuit current is less than a threshold value. Undercertain overcurrent events it may be more favorable to interrupt acircuit using by disconnecting both contactors, whereas under othercircuit currents (e.g., where damage to a contactor may occur ifdisconnected), it may be favorable to keep one or more contactors closedand blow a fuse.

In first state 402, the contactor control module sets both of thecontactors (e.g., contactors 302 and 304) to an open state in responseto detecting an overcurrent event that is less than the first threshold.For example, the contactors may safely interrupt a current of 2,400 ampseach without becoming damaged. The contactor control module may instructthe contactors to open when the overcurrent event is below 2,400 amps,without causing damage to the contactors. For example, the contactorcontrol module may determine that the electric vehicle has been in acrash (e.g., based on a communication from a crash detection system). Ifthe circuit current is under 2,400 amps when the contactor controlmodule detects the crash, the contactor control module instructs thefirst contactor (e.g., contactor 302) and the second contactor (e.g.,contactor 304) to open. In some embodiments, the time to disconnect thecurrent between the battery module and the load may be the sum of thetime it takes the control module to control the contactors (e.g., 50 ms)plus a time required by the contactor to open after receiving thecontrol signal (e.g., 25 ms). Because the first contactor and the secondcontactor open without causing or waiting for the fuses to blow, thesystem is able to more quickly disconnect the battery module from theload than a comparable system comprising only fuses. Furthermore,because the contactors were opened under a normal operating current(e.g., less than the first threshold current), the contactors and fusesmay not need to be replaced before the vehicle is returned to service.

In second state 404, the contactor control module sets a first of thetwo contactors to an open state (e.g., contactor 302) and maintains thesecond of the two contactors (e.g., contactor 304) in a closed statewhen the current is above first threshold 408 but below second threshold410. As discussed above, the first threshold may be selected based on amaximum current where the contactor can safely disconnect a circuitunder load without causing damage to the contactor (e.g., 2,400 amps).Because the current is divided equally across both paths in parallel,the contactors may be able to safely disconnect circuit currents under ahigher load, double the normal operating current (e.g., 5,000 amps).However, under such loads, the opened contactor may be damaged upondisconnecting the circuit. In second state 404, when the contactorcontrol module instructs the first contactor to open (e.g., contactor302), the current is routed through the second path (e.g., the pathcomprising contactor 304 and fuse 314). Because the circuit current(e.g., between 2,400 amps and 5,000 amps) greatly exceeds the ratedcurrent of the fuse (e.g., 1,000 amps), the fuse is blown and thecircuit is interrupted. Under such conditions, the first contactor(e.g., contactor 302) may be damaged because the contactor was openedunder a load exceeding 2,400 amps.

In some embodiments, the contactor control module monitors a currentoutput of the battery (e.g., based on a communication from a batterymonitoring system, a motor controller, or by monitoring a change incurrent over time and may determine that the change in current over agiven time period exceeds a predefined value). For example, thecontactor control module may detect a soft short, such as a powertrainovercurrent event having a circuit current between the first threshold,2,400 amps, and the second threshold, 5,000 amps. In some embodiments,the time to interrupt the current between the battery module and theload may be the sum of the time for the control module to control thecontactors (e.g., 50 ms) plus a time required by the contactor to openafter receiving the control signal (e.g., 25 ms) plus a time requiredfor the fuse to blow at the circuit current (e.g., 0.1 s). Because ofthe thermal nature of fuses, the interruption time may increasingly dropas the circuit current increases.

In some embodiments, in response to detecting a vehicle fault condition,such as a soft short, the battery system may run the car in a reducedpower mode (e.g., by utilizing 50% of the normal operating current).Under the reduced power mode, the battery system may set the firstcontactor to an open state and the second contactor to a closed state,thereby reducing the maximum operating current of the battery system byhalf. In such embodiments, the battery system may operate in conjunctionwith other systems of the car, such as the motor controller, to maintainthe circuit current below the reduced maximum operating current.

In third state 406, when the circuit current is above second threshold410, the contactor control module maintains the first contactor (e.g.,contactor 302) and the second contactor (e.g., contactor 304) in aclosed state. For example, when the overcurrent event exceeds 5,000 amps(e.g., based on a hard short between the most positive switched terminalof the battery and the most negative switched terminal of the battery),the contactor control module may keep the first contactor and the secondcontactor closed, thereby causing fuses 312 and 314 to blow. In thirdstate 406, the disconnection time is highly dependent on thecharacteristics of the fuse. For example, during an overcurrent event of5,000 amps, the disconnection time for the two fuses may be an order ofmagnitude greater than the disconnection time during an overcurrentevent at 20,000 amps.

In some embodiments, the battery system may additionally comprise atleast one contactor electrically coupled to a terminal of the batterythat is unfused (depicted as contactors 110 in FIG. 1 and as contactors204 in FIG. 2 ). For example, the battery system may comprise a fourthand a fifth contactor, each having a respective first terminalelectrically coupled in parallel to a terminal of the battery (e.g., anegative terminal of the battery). The fourth and fifth contactors mayeach comprise a respective second terminal that is coupled in parallelto a busbar. The busbar may be electrically coupled to the load. In someembodiments, the contactor control module controls the state of thefourth and fifth contactors as described above in accordance with FIG. 4.

Although the above examples are discussed with respect to a dualcontactor and dual fuse configuration, one or more contactors may beused. For example, some embodiments include three contactors having afirst terminal electrically coupled in parallel to a first batteryterminal and a second terminal electrically coupled in series to a firstterminal of a respective fuse. A second terminal of the respective fusesmay be electrically coupled in parallel and to a load. A second batteryterminal may be electrically coupled to one or more contactors (e.g., anunfused parallel combination of three contactors). Each of thecontactors may comprise a respective contactor control terminal, and acontactor control module may control setting the contactors to an openor a closed state during an overcurrent event or a crash to minimize adisconnection time between the battery module and the load.

The foregoing is merely illustrative of the principles of thisdisclosure, and various modifications may be made by those skilled inthe art without departing from the scope of this disclosure. Theabove-described embodiments are presented for purposes of illustrationand not of limitation. The present disclosure also can take many formsother than those explicitly described herein. Accordingly, it isemphasized that this disclosure is not limited to the explicitlydisclosed methods, systems, and apparatuses, but is intended to includevariations to and modifications thereof, which are within the spirit ofthe following claims.

What is claimed is:
 1. A battery system comprising: a first switch and afirst fuse coupled in parallel to a second switch and a second fuse; anda switch controller configured to: set the first switch to an open statewhile maintaining the second switch in a closed state in response todetecting a load current above an amperage.
 2. The battery system ofclaim 1, wherein the switch controller is further configured to:maintain the first switch and the second switch in the closed state whendetecting the load current below the amperage.
 3. The battery system ofclaim 1, wherein the first fuse and the second fuse are electricallycoupled in parallel to a battery.
 4. The battery system of claim 1,wherein the first switch and the second switch are electrically coupledin parallel to a load.
 5. The battery system of claim 4, wherein theload is an electric motor of an electric vehicle.
 6. The battery systemof claim 5, wherein a current rating of the first fuse and the secondfuse is one half a maximum operating current of the electric vehicle. 7.The battery system of claim 1, wherein: the first switch is coupled inseries with the first fuse; and the second switch is coupled in serieswith the second fuse.
 8. The battery system of claim 1, furthercomprising: a third switch, wherein the first fuse and the second fuseare electrically coupled in parallel to the third switch.
 9. The batterysystem of claim 8, wherein the third switch is electrically coupled to acharging port of an electric vehicle.
 10. The battery system of claim 1,wherein the amperage is equal to the maximum disconnect current of thefirst switch and the second switch.
 11. The battery system of claim 1,wherein the battery system is located within an electric vehicle.
 12. Amethod for controlling a battery system comprising: setting a firstswitch to an open state while maintaining a second switch in a closedstate in response to detecting a load current above an amperage,wherein: the first switch and a first fuse are coupled in parallel tothe second switch and a second fuse.
 13. The method of claim 12, furthercomprising maintaining the first switch and the second switch in theclosed state when detecting the load current below the amperage.
 14. Themethod of claim 12, wherein the amperage is a first amperage, the methodfurther comprising setting the second switch to an open state inresponse to detecting the load current above a second amperage greaterthan the first amperage.
 15. A vehicle comprising: a first switch and afirst fuse electrically coupled in parallel to a second switch and asecond fuse; a battery electrically coupled in parallel to the firstfuse and the second fuse; one or more electric motors electricallycoupled in parallel to the first switch and the second switch; and aswitch controller configured to: set the first switch to an open statewhile maintaining the second switch in a closed state in response todetecting a load current above an amperage.
 16. The vehicle of claim 15,wherein: the first fuse is electrically coupled in series to the firstswitch; and the second switch is electrically coupled in series to thesecond switch.
 17. The vehicle of claim 15, wherein the switchcontroller is further configured to: maintain the first switch and thesecond switch in the closed state when detecting the load current belowthe amperage.
 18. The vehicle of claim 15, wherein the amperage is equalto the maximum disconnect current of the first switch and the secondswitch, and wherein a current rating of the first fuse and the secondfuse is one half a maximum operating current of the one or more electricmotors.
 19. The vehicle of claim 15, further comprising a third switchelectrically coupled in parallel to the first fuse and the second fuse.20. The vehicle of claim 19, wherein the third switch is electricallycoupled to a charging port of the vehicle.